MBE成長n-GaAsのLOフォノン-プラズモン結合モードによるラマン散乱

概要

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Ramam scattering spectra are measured for n-GaAs epitaxial films grown on the semiinsulating GaAs substrate by the molecular beam epitaxy (MBE) method. The scattering intensity of LO phonon mode decreases with increase of the electron density and the scattering by LO phonon-plasmon coupled modes (L+, L-) are observed when the electron density is above 3×10^17cm^-3. The dependence of L+ mode frequency on the electron density shows a good agreement with the Drude theory considering electron-hole plasma. The frequency of L- mode is shown to shift little because the mode is in the Landau damping region. A pure LO phonon mode from the surface depletion layer is observed even in the heavily doped sample and the relation between the surface depletion depth and the scattering intensity is explained by assuming simple model.
東海大学の論文